The present invention relates to apparatus for attaching fibrous filtering materials to duct work, and more particularly to the attachment of such fibrous filter material to the air intake aperture of an electronic chassis, and specifically a chassis which is cooled by fan-forced air.
The majority of electronic chassis which include fans for forcing air circulation over electronic components for cooling such components include no air filtration system, so that impurities are drawn over the components. Such impurities gather on components within the electronic chassis, particularly in locations of partial air stagnation, and in time develop a film over the electronic components, heat sinks, and other elements. The result of such an impurity layer is a substantial reduction in the forced conduction heat dissipation from the elements, since this impurity layer offers a substantial thermal resistance between the components and the flow of cooling ambient air.
The primary reason for the failure of manufacturers to place proper filters on such chassis is the difficulty and expense of constructing a sheet metal enclosure for surrounding the perimeter of filter elements to support these elements and permit their removal for cleaning or replacement. Such sheet metal supporting structures inhibit the design of electronic chassis since they must extend beyond the normal chassis dimensions. In addition, since many chassis are drawer mounted in large consoles, it is often difficult to provide sufficient access to the rear of the chassis to permit filter replacement.
Even in those instances where manufacturers have gone to the expense, both in design and fabricating terms, to provide filtration systems on electronic chassis, the relative difficulty of removing filters for cleaning or replacement has resulted in the failure of operators and maintenance personnel to adequately maintain the filtration system. As a consequence, the filters are often left uncleaned for extended periods of time such that the filter becomes clogged and impedes airflow. This results in excessive temperatures within the electronic chassis which cause component failure. Alternatively, the filter is simply removed altogether so that, as explained above, a layer of impurities is permitted to build up on the components.